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streetkit

92 Sc400 Sputtering/stalling

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The wife was driving the SC yesterday and it started acting up on her. She said that it cranked a little longer than usual to fire up in the morning but then ran fine most of the day. Later in the afternoon, it sputtered and stalled at a stop light. She put it park and fired it right up with no problem. It did not act up again. I took it out last night and tried to duplicate the problem but got nothing. It ran great. Any ideas as to what it might be? I'm thinking bad gas, or a fuel filter that is clogging up? Car is bone stock except for a K&N filter in the original air box.

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Was it raining or humid where you are? Sometime the cold to warm will cause condensation so may be condensation in the distributor? ECU might do that to but it is expensive piece to replace so try the tune up first if you don’t recall ever changing the plugs or the distributor caps.

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The Soarer has a complex self diagnostic system, the simple readout is displayed on the bottom of the combination meter (speedo), more in depth interrogation can be performed using the diagnostics mode. This is accessed by inserting a jumper (short length of wire or "U" shaped paper clip into the Diags Port (shown above) shorting out the relevant terminals.

The following article courtesy of Steve Janda, Startrade:

"Engine diagnostics can be run by placing a jumper in the engine diagnostics connector between E1 and TE1 terminals (for location of terminals see the label inside the diagnostics connector cover). A straightened up paper clip can be used as a jumper but must be inserted very deep in the terminals. In case of Soarer GT or LTD without the EMV screen, when ignition is switched on error code/s will be displayed in the combination meter on the LCD screen normally showing the time. At first a Japanese message appears indicating the diagnostics mode and when SCROLL button is pushed repeatedly, condition of engine ECU and transmission ECT will show as either Good or N/G (no good). If N/G appears, wait for up to 2 minutes for the display of the actual numerical error code/s. If more than one error code is stored, all will be shown in succession with breaks between them. For example, Code 78 shows problem with the Fuel Pump Control Signal."

http://web.ukonline.co.uk/soarertt/electrical.htm

These are RHD cars so - the fuel pump ecu will be on the driver side. Check the link or read further below.

The fuel pump ECU switches the fuel pump between 9v Low fuel delivery and 12v High fuel delivery depending on the running conditions.

Soarer Fuel pump ECU with cover off:

All the components and circuit board are epoxy bonded making component replacement !Removed! difficult or near as damn it impossible to achieve without breaking something

ECU Symptoms:

The car failing to start when warm is normally the first indication that the fuel pump ECU is playing up, some time afterwards it might exhibit other faults, misfire under load (fuel starvation), starting up and then dying, this can be quickly checked out using the routine below. A replacement ECU is about £180 +vat, I managed to get a secondhand one for £70 from a breaker and it is working fine. The ECU is located behind the passenger rear side panel (the arm rest bit), take out the rear seats and side panel, the ECU is bolted to the frame, (15 minute job).

The following article courtesy of Steve Janda, Startrade:

"The fuel pump can be forced to operate in the high voltage setting by placing a jumper in the engine diagnostics connector between FP and +B terminals (for location of terminals see the label inside the diagnostics connector cover). A straightened up paper clip can be used as a jumper but must be inserted very deep in the terminals. This function is useful for checking that the fuel pump is not faulty (it can be heard running with the ignition on) and also to make the car mobile in case the fuel pump ECU is faulty. We strongly advise against driving the car for prolonged periods with the jumper inserted as the current draw of the pump in its high setting is about 7.3A and the pump may not have been designed to handle the load permanently and may overheat and seize, creating more (expensive) problems. At idle and under light loads the engine may be running rich due to increased fuel pressure"

All props to London Bill and the TIF group for this information.

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Haven't had a chance to do anything to the car yet but it has stalled a couple more times since the first episode. I have a lso noticed that the idle RPM can sometimes be eratic. Would a faulty throttle position sensor cause a problem like this?

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fuel pump, or ignition module....ignition module is expensive and the sc4 has two of them, i'd check the fuel pump first

no throttle has nothing to do with stalling....not to my knowledge at least.

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I have a 95 SC400 in the United States...and it used to stall at idle when the A/C was turned off, whcih means the defroster will do the same...My mechanic said to simply clean the idle control Unit, or replace it...Lexus dealers-$600 or so..

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I would check the fuel pump and the fuel filter. A couple of months ago, someone hit me from the back, and my RPMs dropped eventually stalled. The problem lingered for a few more days, and then cleared up. I later found out my filter was filthy, so I replaced it. Hasn't happened anymore.

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I have a 95 SC400 in the United States...and it used to stall at idle when the A/C was turned off, whcih means the defroster will do the same...My mechanic said to simply clean the idle control Unit, or replace it...Lexus dealers-$600 or so..

I have the same problem, please tell me how to clean idle control unit and where it locate.

V/r

Khoi Nguyen

SC400 1995

kknguyen1168@yahoo.com

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I have a 95 SC400 in the United States...and it used to stall at idle when the A/C was turned off, whcih means the defroster will do the same...My mechanic said to simply clean the idle control Unit, or replace it...Lexus dealers-$600 or so..

I have the same problem, please tell me how to clean idle control unit and where it locate.

V/r

Khoi Nguyen

SC400 1995

kknguyen1168@yahoo.com

He just got the idle control unit, which is a module located in front of the Air Filter intake hose and clean it out somehow..I wasn't really paying attention as to how he cleaned it.

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